If your devices only support up to 4K at 60Hz, a "premium high-speed" HDMI cable (18Gbps, HDMI 2.0) is perfectly fine. Again, just avoid really old or thin cables. Early HDMI cables (HDMI 1.4 or older ...
The most recent scammy gadget that came across my workbench was an "advanced electromagnetic antifreeze snow removal device." A relative of a friend of mine bought the device, wondered why it didn't ...